Electric Submersible Pumps are sometimes deployed in areas where externally-supplied electric power, or mains power, is not reliable. Power outages, also referred to as short mains power glitches can cause significant reductions in pump production. In downhole applications, in which the submersible pump moves liquids, e.g., hydrocarbons, up along a piping column extending from the surface to the bottom of the well, while the pump is operating there is a column of liquid in the piping column. If the power to the pump is interrupted for long enough, the liquid could begin to drain back down the piping column causing the vanes of the submersible pump to backspin. In such an instance, the pump cannot be restarted while the pump backspins as the tubing fluid column drains.
Thus, there could be significant downtime and lost production because it would be necessary to wait until the entire piping column drains before the submersible pump could be restarted. Waiting for the entire piping column to drain is necessary once the pump motor starts backspinning, because an attempt to accelerate the motor while it is backspinning to its normal forward motion will cause regeneration, and likely trip the pump drive on DC bus overvoltage.
Embodiments of the invention provide a solution to the problem described above. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.